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Classification of river regimes: A context for hydroecology

Hydrological Processes

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DOI: 10.1002/1099-1085(200011/12)14:16/17<2831::AID-HYP122>3.0.CO;2-O

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Abstract

Over the past 30 years, ecologists have demostrated the importance of flow and temperature as primary variables in driving running water, riparian and floodplain ecosystems. As it is important to assess the size and timing of discharge variations in relation to those in temperature, a method is proposed that uses multivariate techniques to separately classify annual discharge and temperature regimes according to their 'shape' and 'magnitude', and which then combines the classifications. This paper: (i) describes a generally applicable method; (ii) tests the method by applying it to riparian systems on four British rivers using a 20-year record (1977-97) of flow and air temperature: (iii) proposes a hydroecological interpretation of the classification; (iv) considers the degree to which the methodology might provide information to support the design of ecologically acceptable flow regimes. 'Regimes' are defined for discharge and air temperature using monthly mean data. The results of applying the classification procedure to four British rivers indicates that the 'typical' regimes for each of the four catchments are composite features produced by a small number of clearly defined annual types that reflect interannual variability in hydroclimatological conditions. Annual discharge patterns are dominated by three 'shape' classes (accounting for 94% of the station years: class A, early (November) peak; class B, intermediate (December-January) peak; and class C, late (March) peak) and one 'magnitude' class (70% of the station years fall into class 3, intermediate), with two subordinate 'magnitude' classes: low-flow years (18%) and high flow years (12%). For air temperature, annual patterns are classified evenly into three 'shape' and four 'magnitude' classes. It is argued that this variety of flow-temperature patterns is important for sustaining ecosystem integrity and for establishing benchmark flow regimes and associated frequencies to aid river management. Copyright ?? 2000 John Wiley & Sons, Ltd.Over the past 30 years, ecologists have demonstrated the importance of flow and temperature as primary variables in driving running water, riparian and floodplain ecosystems. As it is important to assess the size and timing of discharge variations in relation to those in temperature, a method is proposed that uses multivariate techniques to separately classify annual discharge and temperature regimes according to their `shape' and `magnitude', and which then combines the classifications. This paper: (i) describes a generally applicable method; (ii) tests the method by applying it to riparian systems on four British rivers using a 20-year record (1977-97) of flow and air temperature; (iii) proposes a hydroecological interpretation of the classification; (iv) considers the degree to which the methodology might provide information to support the design of ecologically acceptable flow regimes. `Regimes' are defined for discharge and air temperature using monthly mean data. The results of applying the classification procedure to four British rivers indicates that the `typical' regimes for each of the four catchments are composite features produced by a small number of clearly defined annual types that reflect interannual variability in hydroclimatological conditions. Annual discharge patterns are dominated by three `shape' classes (accounting for 94% of the station years: class A, early (November) peak; class B, intermediate (December-January) peak; and class C, late (March) peak) and one `magnitude' class (70% of the station years fall into class 3, intermediate), with two subordinate `magnitude' classes: low-flow years (18%) and high flow years (12%). For air temperature, annual patterns are classified evenly into three `shape' and four `magnitude' classes. It is argued that this variety of flow-temperature patterns is important for sustaining ecosystem integrity and for establishing benchmark flow regimes and associated frequencies to aid

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Classification of river regimes: A context for hydroecology
Series title:
Hydrological Processes
DOI:
10.1002/1099-1085(200011/12)14:16/17<2831::AID-HYP122>3.0.CO;2-O
Volume
14
Issue:
16-17
Year Published:
2000
Language:
English
Publisher:
John Wiley & Sons Ltd
Publisher location:
Chichester, United Kingdom
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Hydrological Processes
First page:
2831
Last page:
2848